The traditional snow disk of a ski staff consists of a circular peripheral hoop and, attached to this, leather strips crossing at the center of the disk. At the crossing point the staff has been attached. The advantages of this type of disk are that a large surface area is obtained as well as elasticity of the central area of the disk. However, on hard race trails, for instance, the large disk area is not needed and it may even be objectionable owing to resistance of air. In addition to this, the traditional disk type is comparatively heavy, expensive and poorly suited for series production. Accordingly, in recent time, disks of plastic material have increasingly replaced this traditional disk type.
A feature common to all disk arrangements of prior art is a fairly symmetrical construction. Now the introduction of plastic disks has resulted in a new drawback expressly due to the increased rigidity of the disk. When during the pushing motion, the staff is inclined forward, the leading edge of the disk exerts a counterforce, thus creating the risk that the spike part may rise out of the snow and the staff may slip backwardly. It is further noted that the staff is affected over its entire length by a moment causing it to curve, whereby the skiing is retarded and there is an increased risk of buckling. As a result, there is need of dimensioning for greater strength and increased weight of the staff. In attempts to correct this matter e.g. by making the central part of the disk as elastic as possible, the result is e.g. in the case of plastic disks that short-lived disk designs susceptible to damage are obtained, because known types of plastic cannot endure a continuous, severe deformation. Alternatively, one may arrive at expensive and complicated designs in which the disk has been made articulated or has been attached to the staff to be as easily turnable as possible. It has also been attempted to solve the problem in that the disk and the spike part of the staff have been bent at a given angle against the longitudinal axis of the staff so that when the staff is slightly forwardly inclined, the disk lies in the plane of the ground surface and the spike part is perpendicular against this plane. In this manner, the problem mentioned has been somewhat alleviated, but it has not been totally eliminated. In addition, when the staff is formed to be angulated as has been described, this causes a need for stronger dimensioning of the staff and results in an increased weight.
The object of the present invention is to provide an improved snow disk which is free of the drawbacks mentioned and which, in spite of this, has a design which is as simple, light, durable and inexpensive as possible. The snow disk according to the invention has been found to provide an unexpected solution.